$ Linux Command

System

setpci

Configure PCI device registers.

pcihardwaredeviceconfiguration

Additional Notes

setpci is a utility for querying and configuring PCI (Peripheral Component Interconnect) device configuration registers. It is part of the pciutils package alongside lspci. The PCI configuration space contains registers that control device behavior, such as interrupt settings, memory addresses, and vendor-specific features.

This tool is intended for advanced hardware debugging and development. Incorrectly modifying PCI configuration registers can cause system instability or hardware damage. It should only be used when you understand the specific register you are modifying and its effects.

Syntax

setpci [options] devices operations...

Parameters

  • devices: PCI device selector (e.g., 0:1f.0 for bus:device.function).
  • operations: Register read/write operations (e.g., COMMAND.w=0x07).

Common Options

  • -s [[[[domain]:]bus]:][slot][.func]: Select devices by bus/slot/function.
  • -d [vendor]:[device]: Select devices by vendor and device ID.
  • -v, --verbose: Show verbose output.
  • -D, --dump: Dump all configuration registers for matching devices.
  • -G, --generate: Generate output suitable for parsing.
  • -M, --map: Show PCI memory mapping.

Operations Format

Register operations use the format:

register.operation=value
  • register: Hex offset of the configuration register (e.g., 10, 3c).
  • .operation: b (byte, 8-bit), w (word, 16-bit), l (long, 32-bit).
  • =value: Write the specified value to the register.
  • No =value: Read the register value.

Examples

setpci -s 0:1f.0 COMMAND.w

Read the command register for PCI device at bus 0, device 31, function 0.

setpci -s 0:1f.0 COMMAND.w=0x07

Write 0x07 to the command register (enable I/O, memory, and bus mastering).

setpci -d 8086:100e 10.l

Read the 32-bit value at offset 0x10 for any Intel (8086) device 100e.

setpci -D -s 0:02.0

Dump all configuration registers for the device at bus 0, device 2, function 0.

Practical Notes

  • The lspci command lists PCI devices with their bus:device.function addresses.
  • Register names (COMMAND, STATUS, REVISION) are defined in /usr/share/pci.ids.
  • Hex register offsets can be used instead of names: setpci -s 0:1f.0 0x04.w.
  • Always read a register before writing to verify you have the correct device.
  • Changes to PCI configuration registers are lost after a system reboot.
  • Use -D to explore available registers before making changes.